I need make a decision which table should be use in join statement depend on values in another table
I tried using CASE and COALESCE but can't achieve any success.
TableA has A and B and C and many other columns
TableB has ID and NAME columns
TableC has ID and NAME columns
My select statement is;
Select A.D, A.E, A.F From TableA A
If A.E = 1 then the following join should be used
left outer join TableB B ON A.B = B.ID
and B.NAME should be returned in the select statement
If A.E = 2 then the following join should be used
left outer join TableC C ON A.B = C.ID
and C.NAME should be returned in the select statement
Just add your conditions to the joins, and then use a case statement to pull the correct field to your result set e.g.
select A.D, A.E, A.F
, case when B.[Name] is not null then B.[Name] else C.[Name] end [Name]
from TableA A
left outer join TableB B ON A.B = B.ID and A.E = 1
left outer join TableC C ON A.B = C.ID and A.E = 2
Join tablea with the union of tableb with an extra column with value 1 and tablec with an extra column with value 2 and apply the conditions in the ON clause:
select
a.D, a.E, a.F, u.NAME
from tablea a
left join (
select *, 1 col from tableb
union all
select *, 2 col from tablec
) u on a.B = u.id and a.E = u.col
Related
I have two tables and I want to select all values from "TABLE A" that have a different value in a column from "TABLE B".
I tried this
SELECT A.* FROM tableA A
left join tableB B ON A.id = B.id WHERE B.column <> 1;
But this just return the value that I want to ignore.
SELECT A.*
FROM tableA A
INNER JOIN tableB B
ON A.id = B.id
WHERE B.column != 1;
or
SELECT A.* FROM tableA A WHERE A.Id NOT IN (SELECT B.Id FROM tableB B WHERE B.column != 1)
Depends on your SQL you can use <> or !=
I would suggest not exists:
SELECT A.*
FROM tableA A
WHERE NOT EXISTS (SELECT 1 FROM tableB B WHERE A.id = B.id AND B.column = 1);
Using a JOIN can result in duplicated rows, if more than one row in B matches the JOIN condition.
I have two tables that I want to conditionally join.
Basically, when the Type column from table A ='First' then table A should join to table B on a.ID = b.ID COLLATE Latin1_General_100_CS_AS, but when the Type column from table A ='Second' then table A should join to table B on a.Name = b.Name.
I am putting dummy data below so that you can get a sense of what I am trying to accomplish.
You can use ored conditions:
select a.*, b.amount
from tablea a
inner join tableb b
on (a.type = 'First' and b.id = a.id)
or (a.type = 'Second' and b.name = a.name)
I've got two queries that return single result.
They look something like this
// query 1
SELECT A.id FROM tableA A
INNER JOIN tableB B
ON B.id = A.id
WHERE b.status = 'ACTIVE'
// query 2
SELECT C.id FROM tableC C
WHERE c.status = 'ACTIVE'
How to combine them and make return the pair of values instead of one value from different queries? I mean to get something like [A.id, C.id]
Currently I have to use two queries in the applications and I want to combine them into one.
I think like this will do
SELECT (SELECT A.id FROM tableA A
INNER JOIN tableB B
ON B.id = A.id
WHERE b.status = 'ACTIVE'
) as 'query1',
(
SELECT C.id FROM tableC C
WHERE c.status = 'ACTIVE'
) as 'query2'
As your question is not clear, so i assume that you either needids from mentioned queries in one row or in different rows, you can use union all/union (provided that datatypes are compatible or implicitly convertible and duplicates or allowed or not) as below.
Combining Result in different rows.
SELECT A.id
FROM tableA A
INNER JOIN tableB B
ON B.id = A.id
WHERE b.status = 'ACTIVE'
union all
SELECT C.id
FROM tableC C
WHERE c.status = 'ACTIVE'
Combining Result in Single Row.
select max(id1), max(id2)
from(
SELECT A.id as id1, NULL as id2
FROM tableA A
INNER JOIN tableB B
ON B.id = A.id
WHERE b.status = 'ACTIVE'
union all
SELECT NULL, C.id
FROM tableC C
WHERE c.status = 'ACTIVE'
) t;
SAMPLE DEMO
You can run following query which work fine for me:
select t1.id as aid ,t2.id as cid
from (
SELECT A.id
FROM tableA A
INNER JOIN tableB B ON B.id = A.id
WHERE b.status = 'ACTIVE'
) t1
full outer join (
SELECT C.id
FROM tableC C
WHERE c.status = 'ACTIVE'
) t2 on t1.id=t2.id
You can join your second query with your first query as follows, so that you will get two (A.id, C.id) values in one query...
SELECT A.ID,C.ID FROM
(SELECT A.ID FROM table_A A INNER JOIN
table_B B ON A.ID=B.ID WHERE B.STATUS='A')A
INNER JOIN table_c C
ON C.ID=A.ID WHERE C.STATUS='A';
I have two tables Say A and B. A is master table and B is child table, from which I need values as below.
select A.Id, A.Name, B.Path from A,B where A.Id=B.Id
Now, I want to add column of 3rd table which is child of table 'B', say C i.e. C.File.
The value of C.File will be null if C.SubId=B.SubId is false else will return value when condition becomes true.
This is the exact definition of a left join:
SELECT a.id, b.name, b.path, c.file
FROM a
JOIN b ON a.id = b.id
LEFT JOIN c ON b.subid = c.subid
You need to LEFT JOIN your third table from what I can gather.
SELECT A.Id, A.Name, B.Path, C.file
FROM tableA a
INNER JOIN tableB b ON a.id = b.id
LEFT JOIN tableC c ON b.subid = c.subid
Simply Join all the three tables using INNER JOIN
select A.Id, A.Name, B.Path ,C.File
FROM A
INNER JOIN B
ON A.Id=B.Id
INNER JOIN C
ON C.SubId=B.SubId
I have the following tables
Table A
ID "Other Columns"
1
2
3
Table B
ID "Other Columns"
3
4
5
What is the efficient way to return the below result?
Result
ID "Other Columns"
1
2
4
5
A full outer join should work, and only go through each table once. They can be tricky, so test carefully!
SELECT
isnull(A.ID, B.ID) ID
,"Other columns" -- Handle nulls properly!
from TableA A
full outer joing TableB B
on B.ID = A.ID
where not (A.ID is not null
and B.ID is not null)
You want to use left and right join and union them
Select TableA.ID as 'ID','Other Colums'
FROM TableA Left join TableB
ON TableA.ID=TableB.ID
WHERE TableB.ID IS NULL
UNION
Select TableB.ID as 'ID','Other Colums'
FROM TableA Right join TableB
ON TableA.ID=TableB.ID
WHERE TableA.ID IS NULL
You can try like this
SELECT
COALESCE(a.id, b.id),
OtherColumns
FROM #tablea a
FULL JOIN #tableb b
ON a.id = b.id
WHERE a.id IS NULL
OR b.id IS NULL
You can do this with a UNION ALL using a LEFT JOIN to determine if the ID is not in the other table. Keep in mind that the column count and datatypes between the two tables must match up:
Select A.Id, A.OtherColumns
From TableA A
Left Join TableB B On A.Id = B.Id
Where B.Id Is Null
Union All
Select B.Id, B.OtherColumns
From TableB B
Left Join TableA A On A.Id = B.Id
Where A.Id Is Null
Not quite sure what you need with the "Other columns", but you could use EXCEPT:
Select ID from TableA
EXCEPT
Select ID from TableB
If you need Other columns from TableA you could use:
Select ID, OtherColumn1, OtherColumn2 from TableA
where ID not in (select ID from TableB)
(as long as ID cannot be null in TableB)
I broke down each part to be clearer!
select *
into #temp
from
TabA Full outer join TabB
on TabA.ColNameA = TabB.ColNameB
select *
into #temp2
from #temp
where (ColNameA is Null Or ColNameB is null)
select ColNameA from #temp2
where ColNameA Is not null
union
select ColNameB from #temp2
where ColNameB Is not null